The effect of rapid thermal processing (RTP) on TiN coatings deposited by PVD and the steel-turning performance of coated cemented carbide

Monolithic TiN coatings deposited onto cemented carbide cutting tool inserts coated by PVD methods have been subjected to pulsed intense electron beam treatments in the energy range 3–5 J cm −2 . The temperature profiles for this rapid thermal process (RTP) covered the range between fusion of the cobalt binder in the carbide to surface fusion of the TiN coatings. The treatment caused extensive cracking and removed the atomic level defects, vacancies and dislocations, and residual stress. There was some nitrogen loss very close to the surface but no change in the stoichiometry of the bulk of the nitride. No changes were found in the microstructure of the carbide substrate below the coatings. Steel-turning tests showed that treatment of the coatings at the lowest power used, 3 J cm −2 , reduced the flank wear by a factor of about two.